Compressor



Aug. 9, 1927.

1 J. P. lWILDMAN COMPRESSOR l Filed March 26, 1925 2 Sheets-Sheet 131a/vanto@ Aug. 9, 1927. 1,638,674

' J. P. WILDMAN I COMPRESSOR Filed 'March 2e, 1925 2 sheets-sheet 2Patented Aug, 9, 1927.

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COMPRESSOR.

Application filed March 26, 1925.

My invention relates to pumps and compressors, and is especiallydirected to compressors used in a refrigerating system for compressingthe gaseous refrigerant.

ln a compressor of this character, and especially in those compressorsin Which the refrigerant to be compressed is taken in through the crankcase, an excess amount of oil is commonly forced Vup into the Workingbarrel of the cylinder by the pressure of the gas which has leaked pastthe piston into the crank case and the oil thus forced up is pumped outinto the expansion coils. The oil forms a coating on the bore of thecoils which serves as an insulating medium to prevent efficientradiation through the Walls of said coils. The particular object of myinvention therefore is to arrange the parts in a compressor of thischaracter so that its tendency to pump oil out of the crank case will beeliminated in a relatively simple manner.

Another feature to be contended with in compressors of this character is.that the gaseous refrigerant leaks past the piston and into the cankcase and builds up relatively high pressure therein. The crank case mustbe made air-tight to prevent the gas from escaping to the room, and thus.when a relatively high pressure is set up in the crank case, itnecessitates very tight packing and stuffing boxes.

The introduction of ammonia gas mto the crank case also causes the oilto foam and froth and the foaniy particles are easily forced into thecylinder by the pressure of the gas Within-.said crank case. A furtherobject of my invention is to provide deyiees by which the refrigerantabove tl e piston and the lubricant in the crank case can be kept'separate from each other so as not only to prevent pressure from beingbuilt up in the crank case, but alsoto eliminate the harmful effectscaused by the refrigerant be ing` admitted into contact With thelubricant.

My invention may be said to consist in forming the piston element Withtvvo heads and arranging intermediate the said heads, a circumferentialchamber. Said chamber is vented, the contents preferably being Withdrawn through a branch of the intake pipe for the refrigerant, wherebythe refrigerant Vwhich leaks past the piston and enters said chamber, isWithdrawn before it can escape into the crank case. `Excessive pressure,

therefore, is prevented from being set up in Serial No. 18,480.

the crank case Which Would tend to cause the lubricant contained thereinto be pumped out due to a difference in pressure in said crank case, andin the space above the piston during its suction stroke.

To produce a machine, in which the parts are of suoli size as towithstand the constant usage, to which a refrigerant compressor issubjected, experience has proven that the cross-head should be ofgreater size than the piston so that sufficient bearing surface, andlarge enough pins can be provided to Withstand the pressures and Wear towhich these parts are subjected. ln my invention I propose to form theintermediate chamber, herebefore referred to, by causing said spacedpiston and said crossehead each to seal a portion of the bore of thecylinder. When said piston and said cross-head are of unequal size, apumping action vvill be produced ivhich Would cause oil to be Withdrawnfrom the crank case and forced into the Working branch of the cylinder.The object ofmy invention, therefore, is to provide devices by which apiston, and a cross-head in the forni of a piston and of unequal size,can be used in the saine cylinder and by Which the resulting pumpingaction Will be eliminated.

attain' this object by proi'fiding tivo adj acent cylindersWith'cylindrical pistons and crossheads each reciprocating snugly in thebore of each of said cylinders. The piston and crossshead in eachcylinder is connected together by a portion which is smaller indiaineter thansaid bore so as to provide a chamber 4Within said borecircumferentially about said portionv The cross-head and piston in eachcylinder are of unequal sizebut are exactly equal to the correspondingcrossliead and piston in the adjacent cylinder. The connected piston andcross-head in one cylinder is arranged to be reciprocated oppositely tothe corresponding piston and cross-head in the adjacent cylinder. Byproviding a passageway between said adjacent cylinders which connects hechamber in each, I cause the summation of the volume of said cliaiiioersand said passageway to remain constant. rl'his is for the reason thatwhen one piston and cross-head moves downwardly to tend to produce apartial Vacuum inthe chamber vbetween the same, the piston andcross-head in the adjacent cylinder moves upwardly to compress thecontents thereof. inasmuch as the diameter of said parts is relativelythe same in the adjacent cylinders, the displacement ot each exactlycorresponds to the displacement oit the other and there is no resultantchange in the pressure ot the gases therein.

A turther and more specificl objectotmy' invention is to provide a novelvalve arrangement in said compressor, in which the valves are arrangedYwholly within the cylinder head and are removable therewith. The intakeand discharge valves are thus independent'oft hepistons and arepreferably arranged concentric one within the` other,with the intake-vvalve encompassed bythe discharge valve. The'out'er or encompassing`valve is provided with a plurality ot closure elements held, in place bya single spring` controlled element which is arranged to'act uniformlyupon all or closure elements.

The details ot construction and mode oi? operation are hereinafterdescribed with rc'terenceto the accompanying drawings, in which: i

F l is a longitudinal section through a compressor having two cylindersarranged side by side;

Fig. 2 Ais a plan section taken on the line 2-Q ot Fig. l;

Fig. 3 is a plan section taken on the line fl-3 ot lligj. l; and

Fig. /l is a vertical section taken on the line et+-lofllig. l

My compressor" comprises two cylinders a. which are jmounted upon acrank Acase a5 which Vacts/as 'a support therefor. lAs is common inlcranl; casesoi this character, the cranlrcase ior both cylinders is notdivided by a partition and ythus the portion under each cylindercommunicates freely with the other. Said cylinders are preferably castin a single unit and are water aclreted as a. The compressor shown inthe accompanying drawings has two cylind rs in which the piston elementsl; and c reciprocate. Each piston element has two heads and Z22, and cand c2. The heads and c constitute the piston heads which operate in theworking barrels d and e, and the heads 62 and 02 constitrte cross-headswhich reciprocate in the cy A`dricalguides f and g. As can be noted in Fl., the working barrels are substantially smaller' in diameter than thecylindrical guides. The working barrels are separated by a water jacketspace a?, while the cylindrical guides f and g are separated merely by apartition t3 which terminates in a plane substantially in alinement withthe bottom of the skirts,'which constitute the working` barrels d and c.The partition a3 is arranged equidistant,between the bottom portions ofsaid skirts, and thus a communicating passageway 7ir is provided whichconnects the cylindrical guide f; with the cylindrical guideg, Thepiston elements and c are driven in time oppositely with. each other bythe connecting rods el and y, respectivelv.

4 Y K s Y l, t

4, hat is, as shown in l, when the piston leirent 7J is at upper deadcenter, the piston element c is at lower dead center, and thus when theposition ot one is reversed the other one changed similarly. ForY thisre son the spaces above the cross-heads h2 and '02, and below thepistons and c', and the passageway /L 'through the transverse wallportion at ot the cylinder, remain constant even though the pistons oand c are smaller than the' cross-heads o2 and 02.

Vihen theypiston element c moves'downwardly, as shown in Fig. l, and thepiston element Z) rmoves upwardly, the contents ot each of said spacesis permitted to pass through the passages/'ay /l so as to be equal.-ize'din pressure. `When the position of said piston elements changeoppositcly the contents are permitted to pass through said passageway itinto the opp siteside. The pistonsb and c are provided with a pluralityoit sealingA rings 7' and j to prevent the gas in the working barrelfrom escaping` past` said piston. Experience has proved thatl sealingrings'maintain an etlicient seal but permit slight lealrao'e of gas toecaperto the crank case it means are not provided tor catching andreturning the same to the circulatory system. l thus. connect abranch Itof the intake pipe 7c in the communicating .passageway L above thepartition a3. ln saidbranch la, l place a check valve 7c3 which permitssaid gases to be withdrawn 4from said space but prevents the return :Howtherethrough past said check valve'. l/Vhenever the pressure in thesuction pipe 7c becomes lowerV than that in the spaces between pistonsot cross-heads, the check valve A7c3 opens, allowing the passage of gasfrom said spaces into the intake pipe is.

rlhe cross-heads 722 and cl are each provided with singley lsealing` Zand m, which permit a gra-dial passage ot a slight amount of oil toescape, to serve to lubricate all portions above the ring.

The cylinder hea-drU serves as the head Jtor both cylinders and is castin a singleA unit, and is held down to the cylinder casting by studs n.I mount valve cages 0 and p in said head, as shown in Fig. l.

ing?, tubular extensions o2 and 292 extended upwardly therefrom.Saidpdisc portions o and p are recessed in the cylinder blockdirectly-above the .working barrels d and eV and are arranged so'thattheir upper surfaces lie `substantially flat with the upper surface ofsaid cylinders. By arranging said valve cages in this manner,v l amable,by providing` single gaskets g between the cylinder heada andcylinder a,not only to provide a sealing' medium between thev cylinder and saidhead, but also to provide a seal for the valve cag'eaas well. AThis isfor the reason that said A, qg'aslrets extend about theV re-k and l nSaid valve f cages comprise disc portions 0 and 2),liav-v cess in thecylinder in which said disc portion or the Valve cages are seated. Theintake valves r and s are mounted centrally within said tubularextensions 02 and p2 and are preferably of the mushroom type, as shownin Fig. l. Valve springs r and s tend to hold said valves upon theirseats on the undersurface of the disc portions 0 and p, respectively.The intake pipe c connects into a header or gland t which lits upon thetop of said cylinder head and distributes the refrigerant to bothcylinders. The gaskets or packing material u and u about the tubularportions o2 and p2 are held in place by a header or gland t. Saidpacking material or gaskets provide an air-tight passageway between theintake pipe and the working barrels.

The discharge pipes 7a2 are connected to the working chamber throughthree ball controlled ports 'v and w on the working chambers l and e,respectively. Said ports are spaced equidistant about the intake portdirectly above said working chambers and the balls o and w are heldtightly against the seats by springs m and y which bear against holdingrings and y, respectively, in the working' barrels d and e.

A cored out aperture m2 or y2 is arranged about each respective tubularextension o" and p2, respectively, to provide a passageway for thedischarged refrigerant. Sand discharged refrigerant passes from saidcored out portion through the pipe 7a2. The valves and the valve cagesare removable from the cylinder, with the cylinder head, to expedite thegrinding of said valves or replacement of the parts therein.

The operation of my compressor is as follows:

The gaseous refrigerant to become compressed, `is drawn into thecompressor through the intake pipe 7c and is emitted therefrom throughthe discharge pipes L2. The branch intake pipe 7c communicates with themain intake pipe and thus is subjected to suction by the compressor eachtime the piston therein produces a region of reduced pressure and thusthe same condit-ions of pressure are maintained in the space between theheads of the piston elements, and is maintained in the intake pipes.

Starting with the piston element at upper dead center as in the lefthand cylinder in Fig. l, 'the movement of the piston head b downwardlywill cause relatively reduced pressure in the Working barrel CZ willtend `to unseat the intake valve r and permit the gas to be introducedinto said barrel from t-he intake pipe 7c. Vhen said piston headapproaches vlower dead center, and the reduced pressure is compensatedby gas flowing from said intake, the valve spring r will move the valveback upon its seat to prevent further gas from being admitted.

The movement of said piston head upwardly causes the gas to becompressed and when saidcompression is built up to such a degree as toovercome the springs m which hold the ball checks in place, said ballsare lifted from their seat by said pressure and the gas is permitted toflow outwardly into the discharge line k2.

Said piston elements b and 0 move oppositely and thus, While one pistonis compressing the gas and displacing it from a cylinder, the other isdrawing in a charge of gas from the intake line. Such pistons moving intime oppositely to each other, thus causes the volume of the spacebetween the heads of the piston elements to remain constant, as has beenheretofore brought out, because' of the connecting passageway It.

I claim:

n a compressor: two pairs of alined and connected pistons andcrossheads, the pistons of each pair being smaller than the crosshead ofthe same pair; parallel pairs of cylinders for each of said pistons andcrossheads; a wall common to both of the larger cylinders and extendingupwards to termi nate in a space between the smaller cylinders, saidspace being an equalizing passageway between the housings of saidpistons; a crank shaft operating said crssheads oppositely; and meansupon said crossheads to seal the crank case from the space thereabove.

JOHN P. WILDMAN.

